I am looking for some midpipes that will bolt up to stock axelback etc... My bmw performance exhaust is nice, and was curious if I would be able to muster just a bit deeper exhaust note from the exhaust with a nice midpipe.

I know a lot of people sell them, but seems like they charge almost what it costs for the axleback muffler section itself.

Or am i going to need to tack this on my list of products to release to compete with rediculously overpriced bits?

Your local exhaust shop can fabricate you some midpipes for pretty dam cheap. Downpipes and muffler, I'd purchased fabbed, but mid pipes...exhaust shop. That might just run you 100-200, not a ridiculous 1000. They're pipes, not gold.

Has anyone done this yet?
I'm interested to see how a straight midpipe or dual straight midpipes sound.
This is definitely a cheaper alternative to a $1k axleback or even more expensive catback for anyone looking for more sound, and maybe even a little bit more power.

I doubt you will be happy with this mod. The purpose of a resonator is to suppress a resonance. If you look inside the Y pipe from the exit end (see pic) you will see only a band of small holes not more than .75" wide. There does not appear to be any other opening/s. Judging by the way the Performance Exhaust sounds without the resonator (a slight drone at low RPM under load), very little silencing and backpressure is afforded by this device. You will probably end up with a stock sounding system with drone that will be more noticeable since the sound will not be masked by a louder muffler.

well the point wasnt for flow issues etc. The resonator is already gone with the bmw performance mid pipes, I was talking about replacing last set of cats for a tiny bit more noise. Replacing last set of cats with a full midpipe